13 stable releases

2.1.6 Mar 8, 2021
2.1.5 Mar 5, 2021
2.1.4 Feb 28, 2021
1.0.2 Feb 16, 2021

#732 in Web programming

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MIT license

573 lines


Current Crates.io Version

An library for generating BEM style classnames, in Rust.

If you don't know BEM, it is a set of naming conventions for CSS names. You can find a guide on it's naming conventions here.

Using Classnames

There are two main things to import ...

  • ::classnames::classname - A function for creating classnames.
  • ::classnames::Class - A trait all classnames implement. Use this for when you want to pass classnames to places that you want to use them.

The way classnames works, is internally it wraps each Class with a different Class type. Adding on "__child" and "--attr" classes, and so on.

This is to avoid needing to build lots of strings internally, in order to make it more efficient.

The crux of using Classnames ...

  1. You call classname to create a base classname.
  2. You may then call .el to generate a child classname.
  3. You may also call .attr to add on any BEM attributes.
  4. You can then add classes together, to allow printing multiple different classnames in a component.
  5. Finally all of the above; the base class, the child names, attributes, and classes added together. All support being turned into a String, or being printed with ::std::fmt::Display. That's how you get the formatted classname out.

Here is the above again in code ...

use ::classnames::Class;
use ::classnames::classname;

fn example() {
  // 1. Prints "banner"
  let base_class = classname("banner");
  println!("{}", base_class);

  // 2. Prints "banner__header"
  let header = base_class.el("header");
  println!("{}", header);

  // 3. Prints "banner__header banner__header--bold"
  let bold_header = base_class.el("header").attr("bold");
  println!("{}", bold_header);

  // 4. Prints "banner pricing-banner"
  let pricing_banner = base_class + classname("pricing-banner");
  println!("{}", pricing_banner);

  // 5. Prints out HTML with the classes included.
      <div class="{base_class}">
        <h1 class="{header_class}">Pricing Information</h1>

        <p>Example copy</p>
  "#, base_class = pricing_banner, header_class = bold_header);

Passing classnames to other functions

All of the internal Classname types implement ::classnames::Class. They can be passed by using this type, which you can also wrap in an Option for convenience.

For example ...

  use ::classnames::Class;
  use ::classnames::classname;

  pub fn Card<C: Class, Children: Render>(
    class: Option<C>,
    children: Children,
  ) -> impl Render {
    let base_class = classname("card");

    rsx! {
        class={base_class + class}

Example with RSX

Classnames is intended to be used with something else for rendering HTML. For example with the render crate.

This is an example for the HTML to a hypothetical TextInput component, which can be optionally disabled.

  use ::classnames::Class;
  use ::render::{rsx, Render, component};

  pub fn TextInput(
    is_disabled: bool,
    error: &'static str,
  ) -> impl Render {
    let base_class = classname("text-input");

    rsx! {
        <input class={base_class.el("input").maybe_attr("disabled", is_disabled)} type={"text"} />

        <div class={base_class.el("error")}>

        <img src={"/input-icon.svg"} class={base_class.el("icon").attr("large")} />

Running render( true, &"Some error has occured" ) will produce HTML like ...

    <input class="text-input__input text-input__input--disabled" type={"text"} />

    <div class="text-input__error">
      {"Some error has occured"}

    <img src={"/input-icon.svg"} class="text-input__icon text-input__icon--large" />